ABSTRACT
Land suitability of Okoko Item in Bende Local Government Area of Abia State for sustainable rice (Oriza sativa (L.) and Taro (Colocasia esculenta (L.) production was conducted. Free method of soil survey was adopted. Three land suitability evaluation methods: simple limitation, storie index and square root index were adopted for the study to ascertain the most appropriate for the study. Four mapping units (OKIT I, OKIT II, OKIT III and OKIT IV) were delineated in the area. The soils of mapping units (OKIT I, OKIT II and OKIT IV) located at the upland area of the study site were deep, well drained and their textures ranged from LS – SCL, SL – SCL and SCL – C respectively whereas mapping unit OKIT III located at the lowland area was shallow to moderately deep, poorly to imperfectly drained and had a textural class range of CL – C. The bulk densities of the soils of the mapping units were less than the critical limits for root restriction and their total porosities were good. Mapping unit OKIT IV had a significantly higher bulk density with a resultant lower total porosity compared to the other mapping units. The high presence of gravels, stones and boulders in the mapping unit might have influenced the higher bulk density and lower total porosity. The soils were generally acidic, low in total nitrogen, low to medium in organic matter and moderate to high in available phosphorus. Base saturation was low in mapping units OKIT I and OKIT II but high in mapping units OKIT III and OKIT IV. The soils of the mapping units were classified as Typic Rhodudults (OKIT I), Rhodic Paleudults (OKIT II), Mollic Epiaquents (OKIT III) and Typic Plinthaqualfs (OKIT IV). Based on simple limitation and storie index methods, 489.0 ha or 26.0% of the study area were moderately suitable (S2), 246.0 ha or 13.0% of the area were marginally suitable (S3) while 1,150 ha or 61% of the area were not suitable (N) for upland rice production. Based on square root index method, 750.0 ha or 39.7% of the study area were moderately suitable (S2), 195.0 ha or 10.4% were highly suitable (S1) while 940.0 ha or 49.9% were not suitable (N1) for upland rice (Oriza sativa (L.) production. Evaluating the land suitability of the area for taro (Colocasia esculenta (L.) production, results showed that the total study area of 1,885 ha were moderately suitable (S2) based on simple limitation method. Based on storie index method, 923.7 ha or 49.0% of the area were moderately suitable (S2) and 961.4 ha or 51.0% were highly suitable (S1). Whereas based on square root index method, 1,470 ha or 78.0% were highly suitable (S1) while 414.7 ha or 22.0% of the area were moderately suitable (S2) for taro production. Comparing the results of the three methods used, it was observed that the suitability classes assigned by square root method were superior to that of storie index and simple limitation methods. However, it was evident that the three methods were closely related, although storie index and simple limitation methods showed more correlation. Generally, the study area has minor fertility limitation which influenced the level of suitability to both crops. Hence, the suitability and productivity level can be improved with the use of integrated organo-mineral fertilizers. However, the area with drainage limitation could be used for the cultivation of hydrophytes e.g. swamp rice, vegetables.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables x
List of Figures xii
List of Plates xiii
Abstract xiv
CHAPTER
1: INTRODUCTION 1
1.1 Justification of the Study 3
1.2 Objectives of the Study 4
CHAPTER
2: LITERATURE REVIEW 5
2.1 Overview
of Land Evaluation 5
2.2 Evaluation
Systems 6
2.2.1 Land capability classification 9
2.2.2 Soil fertility capability classification 11
2.2.3 Land suitability classification 12
2.2.3.1
Land suitability orders 13
2.2.3.2
Land suitability classes 14
2.2.3.3
Land suitability subclasses 15
2.2.3.4
Land suitability units 15
2.2.4 Other methods of land evaluation 16
2.2.4.1 Simple limitation method and simple limitation
category 16
2.2.4.2 Parametric system 17
2.2.4.2.1 Storie
index 17
2.2.4.2.2
Square root index 18
2.2.5 Land
suitability classification for irrigated agriculture 19
2.3 Rice Production 19
2.3.1 Origin of rice 19
2.3.2 Ecology and phenology of rice 21
2.3.3 Economic status of rice 22
2.4 Cocoyam Production 23
2.4.1 Origin of cocoyam 23
2.4.2 Ecology and phenology of cocoyams ` 24
2.4.3 Economic status of cocoyam 27
CHAPTER
3: MATERIALS AND METHODS 28
3.1 Description of the Study Area 28
3.1.1 Location 28
3.1.2 Climate 28
3.1.3 Vegetation and land use 29
3.1.4 Geology 29
3.2 Field Study 31
3.3 Laboratory Analyses 32
3.3.1 Sample preparation 32
3.3.2 Physical analyses 32
3.3.2.1 Particle size
analysis 32
3.3.2.2 Soil moisture
content 32
3.3.2.3 Bulk
density 
32
3.3.2.4 Total porosity (Pt) 32
3.3.2.5 Macro porosity (Pma) 33
3.3.2.6 Micro porosity (Pmi) 33
3.3.2.7 Air filled porosity (fa) 33
3.3.3 Chemical
analyses 33
3.3.3.1 Soil pH determination 33
3.3.3.2 Organic matter 34
3.3.3.3 Total nitrogen 34
3.3.3.4 Available phosphorus 34
3.3.3.5 Exchangeable acidity 34
3.3.3.6 Total exchangeable bases 34
3.3.3.7 Effective cation exchange capacity
34
3.3.3.8 Percentage base saturation 34
3.4 Soil
Classification 35
3.5 Land
Evaluation 35
3.5.1 Simple
limitation method 35
3.5.1.1 Land suitability evaluation for
upland rice 36
3.5.1.2
Land suitability evaluation for taro (Colocasia
esculenta (L.) 36
3.5.2 Parametric
methods 40
3.5.2.1
Storie index method 40
3.5.2.2
Square root index method 41
3.6 Data Analysis 43
CHAPTER
4: RESULTS AND DISCUSSION 45
4.1 Morphological
Properties 45
4.2 Physical
Properties 50
4.3 Chemical
Properties 61
4.4 Relationship
between Soil Properties of the Study Area 73
4.5 Soil
Classification 75
4.6 Land
Suitability Classification 79
4.7 Comparison of the Land Suitability
Evaluation Methods 91
4.8 Principal Component Analysis of Soil Properties 94
CHAPTER 5: CONCLUSION AND
RECOMMENDATIONS 97
5.1 Conclusion 97
5.2 Recommendations 99
References 100
Appendices 112
LIST
OF TABLES
2.1: Soil and environmental requirements
of cocoyam 26
3.1: Land requirements for suitability
classes for rainfed upland
rice cultivation 38
3.2: Land quality rating for sustainable
taro (Colocasia esculenta (L)-eddoe
type) production 39
3.3: Quantitative land suitability classes for the
different land indices 42
4.1: Morphological properties of OKIT
I and II 46
4.2: Morphological properties of OKIT
III and OKIT IV 48
4.3: Physical properties of mapping unit
OKIT I 51
4.4: Physical properties
of mapping unit OKIT II 54
4.5: Physical properties
of mapping unit OKIT III 57
4.6: Physical properties
of mapping unit OKIT IV 59
4.7: Chemical properties
of mapping unit OKIT I 62
4.8: Chemical properties
of mapping unit OKIT II 65
4.9: Chemical properties
of mapping unit OKIT III 68
4.10: Chemical properties
of mapping unit OKIT IV 71
4.11: Correlations of
soil profile properties in the study area 74
4.12: Soil classification of the study area 76
4.13: Land suitability classification of okoko item for upland rice
production
based on simple
limitation 80
4.14:
Percentage rating of individual factors of land suitability for upland rice
production in Okoko Item 83
4.15: Land
suitability classification of Okoko Item for taro (Colocasia esculenta
(L.) production based on simple
limitation 85
4.16:
Percentage rating of individual factors of land suitability for taro production
in Okoko Item 88
4.17: Comparison of the land suitability
classes of the mapping units based on
the evaluation methods 92
4.18:
Principal components analysis of soil profile properties in the study area 95
LIST
OF FIGURES
3.1: Map of the Study
Area 30
4.1:
Mapping units showing geo-referenced profile location 44
4.2:
Soil map 77
4.3: Land suitability map
of Okoko Item for upland rice production based on
simple limitation and storie index
methods 81
4.4:
Land suitability map of Okoko Item for upland rice production based on
square root index method 84
4.5:
Land suitability map of Okoko Item for taro production based on simple
limitation method 86
4.6:
Land suitability map of Okoko Item for taro production based on storie
Index method 89
4.7:
Land suitability map of Okoko Item for taro production based on square
root index method 90
LIST
OF PLATES
1: Profile 1 (OKIT I)
showing soil profile horizonation 115
2: Profile 2 (OKIT II) showing
soil profile horizonation 118
3: Profile 3 (OKIT III)
showing high water table and shallow depths 120
4: Profile 4 (OKIT IV)
showing boulders, evidence of concretions and plinthite 123
5: Showing rock outcrops
(stones and boulders) on the landscape of mapping
unit OKIT IV 124
6:
Core sampling by C. C. Anozie 125
CHAPTER 1
INTRODUCTION
The major problem of agricultural
development in Nigeria is poor knowledge and appraisal of suitability of
parcels of land for agricultural production. The result is poor farm management
practices, low yield and an unnecessary high cost of production (Aderonke and
Gbadegesin, 2013). In order to avoid this kind of pitfall in our agricultural
production process, there is need to determine land suitability before the
commencement of any agro-based investment. Land is scarce and non-renewable
natural resource which is highly desired, for its competitive uses because it
holds exchange value (Verheye, 2000). Land is an area of the earth’s surface
that consists of the physical environment, which includes climate, relief, soils and underlying geology,
hydrology, plant and animal population, and the result of past and present
human activity (FAO, 1976; 2007; Dent and Young, 1981).
Soil survey is the systematic examination,
description, classification and delineation of soils of an area. Land
evaluation is the interpretation of soil survey data in order that every
hectare of land should be used in accordance with its capability, suitability
and limitations (FAO, 2007). The suitability of soils for a particular crop or
a specific land use is indicated by the kind and extent of soil limitations
that may impede the cultivation of the crop. It is a prerequisite for a
sustainable land use to enhance good crop yield and quality, and improve soil
health management because the knowledge of soil limitations arising from land
evaluation reports provides practical approaches to ameliorating such
limitations before, or during the cropping period (Lin et al., 2005).
Therefore, the need for proper land suitability evaluation before the
commencement of any agricultural project cannot be over emphasized if
sustainable agricultural production and environmental sustainability is to be
achieved. This becomes very vital at this time when precision farming is
gaining wider acceptance and the relevance is particularly more now in the
developing world where land use is very often not related to its capacity
(Senjobi, 2001).
Rice is a staple food crop in Nigeria and
among the candidate crops being promoted under the Agriculture Promotion Policy
(APP) (2016 – 2020) of Buhari’s administration (FMARD, 2016). Rice has become a
cereal that constitutes a major source of calories for the rural and urban
population (Ajiboye et al., 2011). Domestic production of rice in
Nigeria has been reported to be far below demand due to rapid population
growth, reduction in farmlands in terms of size and quality, and poor rice
cultivars (Ajiboye et al., 2011). This led to considerable importation
to augment the deficit in demand.
Cocoyam is a tropical herbaceous tuber
crop, collectively referred to (Colocasia
and Xanthosoma spp). It is cultivated
predominantly as annuals, mainly for their edible starchy storage underground
stems called corms and cormels. Cocoyam is a neglected staple and medicinal
food. It is commonly consumed by diabetic patients in Nigeria and it is scarce
and costly (Chukwu et al., 2009). Cocoyam
has high economic potentials, not only as food (main meal, snacks and adjunct
in thickening soup) but as an agro-industrial raw material for industries such
as pharmaceutical, confectionery, and livestock. It ranks third after cassava
and yam among staple root and tuber crops, in terms of importance, total output
and area under production in Nigeria (FAO, 1990, Kundu et al., 2012). According to Akomas et al. (1987) the bulk of cocoyam produced in Nigeria is consumed
as food; either as a primary product (corm, cormel, leaves and the
inflorescence) or as a secondary product (flour, cake, crisp, and chip). Chukwu
et al. (2012) and Plucknett et al. (1970) stated that among root and
tuber crops in Nigeria, cocoyam is the only tuber crops that all the parts are
edible because the corms and cormels are eaten in various food forms while the flowers
and leaves are commonly used as spice to garnish and flavour food.
Different methods of land evaluation have
been developed. They include, the Land Capability Classification (LCC)
(Klingebiel and Montgomery, 1961), framework for land evaluation (FAO, 1976;
2007), quantitative parametric methods
of Storie Index (Storie, 1976) and Square Root Index (Khiddir, 1986), the
conventional Non Parametric method of
Simple Limitation Method and Simple Limitation Category (Chukwu et al., 2005) which adopts the guidelines of land evaluation framework (FAO,
1976, 2007) as modified by Sys et al. (1991a, 1993) and subsequent
guidelines formulated by Dent and Young (1981) and Van Diepen et al. (1991). The Simple Limitation Method,
Storie Index and Square Root Index were used in attributing suitability class.
Subsequently these methods were compared to ascertain their relationship and to
select the method most appropriate for the study.
According to the guidelines of FAO (1976;
2007), land suitability classification is divided into four categories of
decreasing generalization which are land suitability orders, land suitability
classes, land suitability sub-classes and land suitability units.
1.
Land suitability orders reflect the kind
of suitability and is represented with the symbols S (Suitable) and N (Not
suitable).
2.
Land suitability classes reflect the
degrees of suitability: S1 (Highly Suitable), S2
(Moderately Suitable), S3 (Marginally Suitable), N1 (Currently Not Suitable) and N2
(Permanently Not suitable).
1.1 JUSTIFICATION
OF THE STUDY
·
Domestic production of rice in Nigeria has
been reported to be far below demand due to rapid population growth, reduction
in farmlands in terms of size and quality, and poor rice cultivars (Ajiboye et
al., 2011). These led to considerable importation to augment the deficit in
demand.
·
Rice and cocoyam are major crops commonly
cultivated in the farming systems of the study area; there is need to boost
their production in commercial quantities.
·
Taro (Colocasia
esculenta (L) is a neglected staple and medicinal food (Chwuku et al., 2009) that is threatened with
extinction (Nwosu, 2007; Chwuku et al.,
2009).
·
There is dearth of information on soil
survey and land evaluation for rice and cocoyam production in Okoko Item.
1.2 OBJECTIVES OF THE STUDY
The main
objective of the study was to conduct a soil survey of Okoko
Item, Bende LGA, Abia State,
Nigeria for its suitability evaluation for rice and taro production.
The specific
objectives of the study were to:
·
characterize
the soils of the community with reference to morphological, physical, and
chemical properties;
·
delineate
the distribution of soils in the area;
·
evaluate
the suitability of the area for sustainable rice and taro production;
·
compare
three different methods of land suitability evaluation for sustainable rice and
taro production in the study area.
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